The movie was filmed in the Davidson College Library during the week of Spring Break of 2017. Through the chaos of equipment, actors, extras, and all the technical people it takes to make a movie, the library staff continued to perform their jobs. Some of the staff were asked to submit their head shots to be cast in the film which resulted in one person being asked to be in the film. However, it was inconvenient for staff to take the time away from their jobs to be in the film, so, therefore, no staff person was in the film. But, if you look closely in the shots filmed in the library, there are offices with their blinds down. Staff are behind those blinds working diligently making sure the library still functioned.
Though most of the filming took place in Charlotte, all of the library scenes were filmed in Davidson College's library over the course of spring break, 2017. Every member of the library staff sent in their head shots to be cast in the film, but none of them made it onscreen.
The trivia item below may give away important plot points.
The director originally approached Warren and the others about the film while they were still incarcerated for the crime. The resulting relationship that developed culminated in the final film, after they were released.